The present invention relates, in general, to data storage and, more particularly, to data storage system comprised of multiple data storage devices.
The advances in computing technology and network infrastructure have provided opportunities for transmitting digital media of many forms at high speed. It might be economically feasible and efficient to store media content in one or more storage devices connected to a server and distribute the media content to clients over the network on a real-time or near real-time basis. For example, with the state of art digital compression technology, high quality continuous real-time video display can be maintained with digital video signal transmission rate as low as one megabit per second. Thus, it would be efficient to store digitized video programs on a centralized storage system and deliver the programs to clients, e.g., through Internet, satellite, compact disks, terrestrial broadcast, on an as needed or as requested basis.
A storage device or system server for storing and delivering the video programs requires a high digital data storage capacity. For example, one thousand hours of broadcast quality digital video program content, which is equivalent to about four hundred movies, compressed in accordance with a Motion Picture Experts Group (MPEG) format generally requires approximately one tera-bytes of storage space. Backup storage for preventing data loss will take comparable or even more storage space. To be commercially viable, a server with a centralized storage system may need to have several thousand movies and other video programs stored thereon and ready for delivery to clients on request over the network.
Large storage capacity can be achieved through a data storage system comprised of multiple storage devices. One approach of preventing the storage system from overheating is to attach the storage devices in the storage system to one or more large heat sinks such as, for example, aluminum blocks. Another approach is to arrange the storage devices in the storage system apart from each other and to provide sufficient airflow in the in the space between the storage devices. These approaches will significantly increase the bulkiness, i.e., size and/or weight, of the storage system. Reducing the number of the storage devices in the storage system running simultaneously may reduce the heat generation rate, thereby preventing the storage system from overheating. However, this will adversely affect the operating efficiency of the data storage system.
Accordingly, it would be advantageous to provide a data storage system that has a large data storage capacity and is compact and lightweight. It is desirable for the data storage system to have a high data access rate. It is also desirable for the data storage system to be reliable. It would be of further advantage for the data storage system to simple and inexpensive to operate.
In a general aspect, the present invention provides a data storage system that has a large data storage capacity. In a specific aspect, the data storage system in accordance with the present invention is compact and lightweight. In another specific aspect, the data storage system has a high data access rate. In various other specific aspects of the present invention, the data storage system in accordance with the present invention is simple, reliable, and/or cost efficient.
A data storage system in accordance with the present invention includes an array of data storage devices mounted on one or more trays. The storage devices on each tray form one column of the array. The array may include any number of columns of storage devices. In accordance with an embodiment of the present invention, each column of storage devices are attached to the two opposite sidewalls of a corresponding tray, with the bottoms or tops of the storage devices in close proximity to the floor of the tray. The bottoms or tops of the storage devices and the sidewalls and the floor of the tray form a narrow channel, through which air can flow. A fan is positioned on one end of the tray to generate airflow in the channel, thereby providing efficient cooling of the storage devices.
In accordance with a particular embodiment of the present invention, the tray is mounted on a chassis, on which various components of a data storage and access system, e.g., signal processing circuit, signal transmission circuit, power supply circuit, etc., are mounted. In an embodiment of the present invention where the array includes more than one column, the trays are substantially coplanar and parallel to each other when they are mounted on the chassis. Therefore, the data storage system includes data storage devices arranged in a two dimensional array. In an alternative embodiment, the trays are substantially parallel to each other and arranged into multiple layers. In this embodiment, the data storage system includes data storage devices arranged in a three dimensional array. The airflows in the channels can be generated by a single fan or a plurality of fans.
In accordance with a preferred embodiment of the present invention, the data storage system includes a plurality of hard disk drives mounted on a plurality of trays. The hard disk drives on each tray are substantially aligned and coplanar with each other. The trays with the hard disk drives mounted thereon have a thickness equal to or less than one rack unit (4.445 cm). Therefore, the columns of hard disk drives can slide into slots in a chassis that have a height of one rack unit. In one embodiment, the chassis has slots on a single layer. In another embodiment, the chassis has slots on multiple layers. The height of the data storage system is approximately equal to one rack unit multiplied by the number of layers. The length of the data storage system is substantially determined by the number of hard disks in each column of the array, and the width of the data storage system is substantially determined by the number of columns in the array. In yet another embodiment, the data storage system includes multiple chassis mounted on a rack, with each chassis having slots in a single layer.
By way of example, a data storage system in accordance with an embodiment of the present invention includes twelve hard disks mounted on four trays, there by forming a two dimensional array having four columns, with three hard disks in each column. The array has a dimension no greater than 45 cm in width, 50 cm in depth, and 4.5 cm in height. The array may be mounted on a chassis or a board with signal processing circuits, power supply circuits, cooling fans, etc, the whole board may have a depth of approximately 75 cm. With each hard disk having a memory of 160 giga-bytes (GB), the data storage board has a memory capacity of 1.92 tera-bytes (TB). A server for storing data such as, for example, video program content, may include several such data storage boards stacked on top of each other on a rack.